The present invention relates to a detent apparatus for preventing the rotation of neighboring identical elements which are threaded into their associated body. Typically, the neighboring identical elements may be delivery valve holders which are threaded into the body of a fuel injection pump of a Diesel engine.
A fuel injection pump compresses fuel with its plunger and delivers the pressurized fuel at a predetermined timing and by a predetermined amount through delivery valves which are associated with respective engine cylinders. The fuel is fed under pressure through fuel injection tubings to fuel injectors mounted on the engine cylinders and injected into the engine cylinders forcing the fuel injectors to open.
A delivery valve holder is threaded into the body of the fuel injection pump to retain a delivery valve air-tight within the pump body through a gasket, which is interposed between the inner end of the valve holder and a delivery valve housing. A delivery pipe is connected to the outer end of the valve holder by a cap nut so that it can be removed from the valve holder as is required for the replacement of the fuel injector, for example. While the cap nut is unfastened, it is necessary to prevent the valve holder from being rotated therewith and thereby loosened. If the valve holder is loosened, the air-tight sealing between the valve holder and the valve housing provided by the gasket will be deteriorated to affect the pressure and amount of fuel injection which in turns affects the engine output. Re-fastening the valve holder would little aid in regaining the original air-tight sealing.
A conventional detent arrangement designed to keep the delivery valve holders from rotation comprises a pair of wedge members which are applied to adjacent valve holders from opposite sides of the latter and fastened together by a bolt and nut assembly. The valve holders are thus held in frictional engagement with the wedge members and thereby prevented from rotation. However, an intricate procedure is necessary for connecting the wedge members together by a bolt and nut assembly while bringing them closer to each other. The intricacy makes it difficult to promote automatic operation which is desired for the assembly of such detent arrangements.